1. Field of the Invention
The present invention relates to a solid-state imaging device, a method of driving a solid-state imaging device and a camera
2. Description of the Related Art
In the solid-state imaging device, a dark defect phenomenon is a problem. As a technique to avoid the dark defect phenomenon, a technique below is disclosed (for example, see JP-A-2004-248304 (Patent Reference 1)).
The technique is a technique that uses a means for correcting an event that performs a differential process depending on the output of a detection circuit. As shown in FIG. 9, generally, a signal is generated in photoelectric conversion done by a means for photoelectric conversion, the signal is inputted to an amplifier transistor to output a signal Vs. The signal Vs contains a signal generated by photoelectric conversion and a reset signal Vn. Therefore, when a differential amplifier reads the signal Vs as the signal generated by photoelectric conversion, the reset signal Vn of a noise component is subtracted therefrom to output the signal generated by photoelectric conversion as a signal Vs−Vn.
Then, when the incident light quantity is stronger than that at Point B, the signal is saturated to output a constant value. When much stronger light enters, the reset level Vn is changed to make the signal Vs−Vn small. This is turned to the dark defect phenomenon.
More specifically, when a very strong light enters a photoelectric converting part, a light leakage noise signal is added to the reset signal of the noise component at the input part of the amplifier transistor due to the light leakage. In the state in the area in which the incident light quantity is stronger than that at Point C, the output of the differential amplifier, Vs−Vn, is made small. When the light leakage noise signal Vn is saturated, the output Vs−Vn of the differential amplifier signal is turned to zero. This state means that even though a really bright subject is imaged, the dark defect phenomenon occurs in which the image is darkened.
This characteristic is utilized to determine whether the light is very strong or not from the area where Vn is varied and from the area where Vs is saturated. This is sufficient that a photo-detection circuit determines whether the signal is corrected from here or not. As shown in FIG. 10, when the signal is corrected, there is a scheme in which the signal is corrected before an analog-digital converter circuit A/D without performing the differential process. Furthermore, as shown in FIG. 11, when a memory is read that stores the value of the analog-digital converter circuit A/D, there is a scheme in which the signal is corrected by a converter circuit to output it, the converter circuit corrects the event that performs the differential process depending on the output from the light level detection circuit.
In the technique shown in FIG. 10, when a dark defect is detected to correct the signal before the analog-digital converter circuit A/D, it is necessary to provide a correction signal circuit, for example, a constant voltage circuit other than a detection circuit, which causes an increase in the circuit scale as the configuration of the dark defect correction circuit.
In the technique shown in FIG. 11, it is necessary to provide a circuit which interrupts the correction signal into the memory, which also causes an increase in the circuit scale. In the circuit system in which analog-digital conversion is performed in each of signal lines, the area is greatly affected.
In any of the techniques before, it is necessary to additionally provide a light level detection circuit exclusive for detecting the dark defect in order to detect the dark defect. In addition, since it is necessary to provide an analog sensing detection circuit in an analog signal path, a problem also arises that an analog signal itself might be adversely affected.